People would use that service instead of Steam, publishers would add annoying DRM to mitigate lost sales, etc etc.
The current illegality of the piracy website prevents them from offering a service as nice as Steam. It has to be a sketchy torrent hub that changes URLs every few months. If it was as easy as changing the url to freesteampowered.com or installing an extension inside the steam launcher, the whole "piracy is a service issue" argument loses all relevance. The industry would become unsustainable without DRM (which would be technically legal to crack, but also more incentivized to make harder to crack).
Copyright does discourage DRM. Even the most egregious DRM these days can be bypassed with minimal effort and is mostly just a nuisance. Take away government enforcement of copyright and how profitable your digital product is will be directly tied to how advanced you are in the DRM arms race.
Steam is the classic example of how this is effective. You compete with pirates by offering what they can't: a reliable, convenient service. DRM becomes more of a hindrance than a benefit in this situation.
Allowing pirates to offer reliable convenient pirate websites that are "so easy a normie can do it" would be a disaster for all the creative industries. You would need to radically change the rest of society to prevent a total collapse of people making money off art.
The current illegality of the piracy website prevents them from offering a service as nice as Steam. It has to be a sketchy torrent hub that changes URLs every few months. If it was as easy as changing the url to freesteampowered.com or installing an extension inside the steam launcher, the whole "piracy is a service issue" argument loses all relevance. The industry would become unsustainable without DRM (which would be technically legal to crack, but also more incentivized to make harder to crack).